1. Field of Invention
The invention relates to a pulley puller. More particularly, it relates to a multi-head, rack and pinion driven pulley puller that has particular usefulness in applications with minimal clearance or minimal access to a pulley.
2. Description of the Related Art
In the art of pulleys, particularly pulleys used in conjunction with belt-driven equipment, it is known that a pulley must frequently be removed from a pulley shaft. In this regard, many belt-driven types of equipment utilize a pulley on a shaft for receiving belt-driven power, the shaft may turn a piece of equipment, or may have an additional pulley for redirecting the rotational force, via a secondary belt, in another direction. Typically, there is a bearing assembly in conjunction with the shaft and pulley(s) which is subject to wear, fatigue, and replacement. Further, it is known that pulleys are often used in conjunction with keyed shafts, a key and cooperating slot being utilized to prevent unwanted slip between the pulley and the shaft. It is known, generally, that force must often be used in the removal of the pulley from the shaft due to conditions including repeated usage, tight tolerances between pulley and shaft creating a tight friction fit, and frequently, the need to remove a pulley from a shaft that is heated through use. However, those skilled in the art will recognize that, due to space constraints, it is often difficult to apply force. Moreover, typical pulley pullers often require a large amount of space around the pulley for placement of known, prior art pulley pullers.
One such example of belt driven equipment that utilizes numerous pulley/shaft/bearing assembly combinations are the mail sorters typically utilized by the postal service. In this regard, pieces of mail, i.e. envelopes, are propelled by pulley-driven belts through various modules, including, without limitation reader modules and stacker modules through a plurality of gates which direct the path of individual pieces of mail into a specific pocket depending upon its destination. Those skilled in these arts will recognize that modern mail sorters handle between 30 and 36 thousand pieces of mail per hour, propelling the individual envelopes at speeds of approximately 154 inches per second. These stacker modules contain multiple pulley/bearing assembly combinations, and, as the common name suggests are often stacked on one another creating very tight spacing in which to work on such pulleys for maintenance purposes. And, it will be appreciated that it is very important to minimize down-time when it is necessary to do maintenance on various pulleys.
And, there are a number of different types of pulley pullers known in the art. For instance, U.S. Pat. No. 1,709,913 issued to Kaplan on Apr. 23, 1929, describes a gear puller comprising a block with a pair of jaws pivotally connected to the block and a jack screw threadably mounted in the block. The jack screw is turned and applies a force to the shaft that the gear or pulley is mounted on in order to pull the gear or pulley off of the shaft. Similarly, U.S. Pat. No. 4,084,305, issued to Chang on Apr. 18, 1978, and U.S. Pat. No. 6,665,918 issued to Williams on Dec. 23, 2003 disclose pulley pullers that are also actuated by a jack screw, or thrust bolt, which serves to drive the hub and attached jaws, or arms away from a shaft on which a pulley is mounted. Kiebler, in U.S. Pat. No. 6,266,860, issued on Jul. 31, 2001, discloses a different structure for engaging a pulley, but also relies on a jack screw to drive the puller away from a shaft on which a pulley is mounted. U.S. Pat. No. 7,927,337 issued to Keller on Apr. 19, 2011, discloses a bone spreader, in the medical arts, that utilizes a rack and pinion to move two spreader bodies either towards or away from each other.
What is missing from the art is a pulley puller that is actuated by a rack and pinion drive allowing for more rapid adjustment than typical jack-screw actuated pulley pullers. Further, missing from the prior art is a rack and pinion driven pulley puller that is adapted to have interchangeable heads allowing for accessing pulleys in a variety of environments.